So-called grid computing connects a plurality of computers on a network such as the Internet to establish one computer system. In a computer (an element computer) as an element of a grid, an application program for grid computing (a grid application or a grid AP) is installed and executed.
As an operating environment of the grid application, for example, a configuration illustrated in FIG. 6A is known. A general OS (a general-purpose OS) is operated on a hardware of the element computer, and the grid application and a general-purpose application are operated on the general-purpose OS. The general-purpose OS is an OS generally available on the market such as Windows (registered trademark of Microsoft Corporation) and Linux.
As another operating environment of the grid application, a configuration adopting a multi OS explained below is known (see Patent Document 1). A general-purpose OS (an independent processing OS), an OS of grid computing (a grid dedicated OS), and a grid middleware are operated on a hardware of an element computer. A general-purpose application (an independent processing application) is operated on the independent processing OS. And, a grid AP is operated on the grid dedicated OS and the grid middleware.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-252629
In general, in grid computing, there are the following problems concerning security of an element computer.
First, when the element computer of the grid computing is provided as a resource or when the element computer uses other resources (hereinafter, during grid use term), the element computer is easily affected by a health state of a grid computing system. In the element computer, there are cases that the general-purpose OS becomes unstable, that a trouble due to an application or a driver occurs, that a file is destroyed, that the computer gets infected with a virus, and that environment setting changes to an inappropriate state. According to my study, this problem occurs because two group of programs, i.e., a group of the grid (dedicated) OS and the grid application and another group of the general-purpose OS and the general-purpose application simultaneously are operated, during grid use term (in other words, operation is not exclusive).
Second, in the element computer, the grid application is executed in a usual environment of use of a user of the element computer. Therefore, during grid use term, there are risks that the general-purpose OS or the general-purpose application is subjected to system manipulation by a virus, and that a worm or information of the general-purpose application flows out from the element computer. According to my study, this problem occurs because, as illustrated in FIG. 6B in an element computer (PC) 100, during grid use term, the grid OS is not bound by access restriction to restrict an access to a hard disk (HDD), for example, and because the grid OS is accessible to all circuits.
Third, in the element computer, during grid use term, an execution environment is in the same state as an execution environment (in other words, a normal operation state) of the general-purpose application. Therefore, in some case, the element computer becomes in an operation state at maximum power consumption, so that power consumption cannot be saved. According to my study, as illustrated in FIG. 6B, this problem occurs because power is equally supplied to all the circuits to make the circuits operable, during grid use term, in the element computer 100.